Fix refferences to System.Memory and System.Bug=ffers (dotnet#9971)

Author: KevinRansom

eng/Versions.props

@@ -85,7 +85,7 @@
     <SystemIoCompressionVersion>4.3.0</SystemIoCompressionVersion>
     <SystemLinqExpressionsVersion>4.3.0</SystemLinqExpressionsVersion>
     <SystemLinqQueryableVersion>4.3.0</SystemLinqQueryableVersion>
-    <SystemMemoryVersion>4.5.3</SystemMemoryVersion>
+    <SystemMemoryVersion>4.5.4</SystemMemoryVersion>
     <SystemNetRequestsVersion>4.3.0</SystemNetRequestsVersion>
     <SystemNetSecurityVersion>4.3.0</SystemNetSecurityVersion>
     <SystemReflectionEmitVersion>4.3.0</SystemReflectionEmitVersion>
@@ -104,8 +104,7 @@
     <SystemThreadingThreadVersion>4.3.0</SystemThreadingThreadVersion>
     <SystemThreadingThreadPoolVersion>4.3.0</SystemThreadingThreadPoolVersion>
     <SystemValueTupleVersion>4.5.0</SystemValueTupleVersion>
-    <SystemBuffersVersion>4.5.0</SystemBuffersVersion>
-    <SystemMemoryVersion>4.5.3</SystemMemoryVersion>
+    <SystemBuffersVersion>4.5.1</SystemBuffersVersion>
     <!-- Roslyn packages -->
     <MicrosoftCodeAnalysisEditorFeaturesVersion>$(RoslynVersion)</MicrosoftCodeAnalysisEditorFeaturesVersion>
     <MicrosoftCodeAnalysisEditorFeaturesTextVersion>$(RoslynVersion)</MicrosoftCodeAnalysisEditorFeaturesTextVersion>